Following on from my slightly OT post of a few weeks ago regarding the
'impossible' H linearity error that I saw on the Delta in-flight LCD screen,
tonight, I saw another. This time it was on an LCD screen at my local bingo
hall. I would guess that it's about a 22", standard 4:3 aspect ratio. Used
to display numbers when they are playing tabletop cash bingo, and winning
cards during normally called bingo. There are many screens around this large
hall, all being fed from the same primary video source, so I think that
incoming signal can be eliminated.

This one had a 'foldover' of about 1.5" at the top left corner. It
progressed across the screen getting less and less, until at the right hand
side, the top of the picture was absolutely normal. The 'foldover' was
extremely non linear. It looked to be very stretched, to the point where you
could see what you would describe as individual scanning or field flyback
lines - if it were a CRT display ...

I thought I was reasonably au fait with the way an LCD screen was driven
from its frame buffer, but I'll be buggered if I can see a way that data
could be read out erroneously, in such a way as to produce a badly stretched
tapering wedge of foldover, across the top of the screen. Anyone seen
anything like *this* one, or have any suggestions how it could occur ... ??

Arfa

In article ,
says...
This one had a 'foldover' of about 1.5" at the top left corner. It
progressed across the screen getting less and less, until at the right hand
side, the top of the picture was absolutely normal. The 'foldover' was
extremely non linear. It looked to be very stretched, to the point where you
could see what you would describe as individual scanning or field flyback
lines - if it were a CRT display ...

I thought I was reasonably au fait with the way an LCD screen was driven
from its frame buffer, but I'll be buggered if I can see a way that data
could be read out erroneously, in such a way as to produce a badly stretched
tapering wedge of foldover, across the top of the screen. Anyone seen
anything like *this* one, or have any suggestions how it could occur ... ??

The screens are probably being fed an analog signal. Some noise or
electronics failure is causing it to improperly sync.

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Arfa Daily wrote:
Following on from my slightly OT post of a few weeks ago regarding the
'impossible' H linearity error that I saw on the Delta in-flight LCD screen,
tonight, I saw another. This time it was on an LCD screen at my local bingo
hall. I would guess that it's about a 22", standard 4:3 aspect ratio.

Imaginary ...

These are old unspent CRT nightmares from an age ago, Arfa, that you
must have been dreaming about with such realism whilst asleep. Except
your mind has updated the display technology to LCD.

Too much wine? Long flight? Exciting Bingo session?

Need to see a declaration that 'ye pinched yourself' while noticing the
effects.

;-)

--
Adrian C

"Adrian C" wrote in message
...
Arfa Daily wrote:
Following on from my slightly OT post of a few weeks ago regarding the
'impossible' H linearity error that I saw on the Delta in-flight LCD
screen, tonight, I saw another. This time it was on an LCD screen at my
local bingo hall. I would guess that it's about a 22", standard 4:3
aspect ratio.

Imaginary ...

These are old unspent CRT nightmares from an age ago, Arfa, that you must
have been dreaming about with such realism whilst asleep. Except your mind
has updated the display technology to LCD.

Too much wine? Long flight? Exciting Bingo session?

Need to see a declaration that 'ye pinched yourself' while noticing the
effects.

;-)

--
Adrian C

Hi Adrian

Nope. Yes. Nope !

No wine on either the flight or at bingo, Yes, it was a long flight, but
that just gave me plenty of time to study the problem on that one (and reach
no conclusions). No - not a very exciting bingo session. I didn't even want
to go, but saying no to the missus when she's decided that is where we are
going - well, work out the consequences for yourself !

However, on a more serious note, the problem observed on this particular
monitor, was quite real. It is a ceiling suspended monitor, and definitely
LCD. For sure, it is being fed with an analogue signal, but so are the other
probably thirty similar monitors distributed throughout the club, and they
all carry the same content at the same time, as I think I said at the
beginning, and no other that I saw was exhibiting the same problem, which
pretty much eliminates the content of the feed. Even if it was a problem
with the signal, I can't for the life of me think what that problem could
be, to cause that symptom. And not any kind of sync issue that I can think
of either. The picture was perfectly stable in both the H and V directions.
Very odd ...

Arfa

"Meat Plow" wrote in message
...
On Mon, 9 Nov 2009 01:09:59 -0000, "Arfa Daily"
wrote:

Following on from my slightly OT post of a few weeks ago regarding the
'impossible' H linearity error that I saw on the Delta in-flight LCD
screen,
tonight, I saw another. This time it was on an LCD screen at my local
bingo
hall. I would guess that it's about a 22", standard 4:3 aspect ratio. Used
to display numbers when they are playing tabletop cash bingo, and winning
cards during normally called bingo. There are many screens around this
large
hall, all being fed from the same primary video source, so I think that
incoming signal can be eliminated.

This one had a 'foldover' of about 1.5" at the top left corner. It
progressed across the screen getting less and less, until at the right
hand
side, the top of the picture was absolutely normal. The 'foldover' was
extremely non linear. It looked to be very stretched, to the point where
you
could see what you would describe as individual scanning or field flyback
lines - if it were a CRT display ...

I thought I was reasonably au fait with the way an LCD screen was driven
from its frame buffer, but I'll be buggered if I can see a way that data
could be read out erroneously, in such a way as to produce a badly
stretched
tapering wedge of foldover, across the top of the screen. Anyone seen
anything like *this* one, or have any suggestions how it could occur ...
??

Arfa


Its as if the signal was distorted before it ever got to the LCD.
Isn't that possible?

Hi Meat. See reply to Adrian above. Here's a little aside you'll no doubt
find amusing ... Got in this afternoon, and number 2 daughter was doing some
door painting for us in the house, and had MTV on. At pretty near full
volume, shaking the house ...

Tonight, I'm watching some TV, and the sound is 'wrong'. A bit quiet, and
slightly 'thin' sounding. Then some incidental music came on the programme,
and it had a very odd 'raspy' sort of a sound to the bass beat. Then I
realised what is wrong. She's only gone and buggered the TV set's built in
sub. Bloody kids. Who needs 'em ?

Arfa

"Meat Plow" wrote in message
...
On Tue, 10 Nov 2009 01:38:17 -0000, "Arfa Daily"
wrote:


"Meat Plow" wrote in message
...
On Mon, 9 Nov 2009 01:09:59 -0000, "Arfa Daily"
wrote:

Following on from my slightly OT post of a few weeks ago regarding the
'impossible' H linearity error that I saw on the Delta in-flight LCD
screen,
tonight, I saw another. This time it was on an LCD screen at my local
bingo
hall. I would guess that it's about a 22", standard 4:3 aspect ratio.
Used
to display numbers when they are playing tabletop cash bingo, and
winning
cards during normally called bingo. There are many screens around this
large
hall, all being fed from the same primary video source, so I think that
incoming signal can be eliminated.

This one had a 'foldover' of about 1.5" at the top left corner. It
progressed across the screen getting less and less, until at the right
hand
side, the top of the picture was absolutely normal. The 'foldover' was
extremely non linear. It looked to be very stretched, to the point where
you
could see what you would describe as individual scanning or field
flyback
lines - if it were a CRT display ...

I thought I was reasonably au fait with the way an LCD screen was driven
from its frame buffer, but I'll be buggered if I can see a way that data
could be read out erroneously, in such a way as to produce a badly
stretched
tapering wedge of foldover, across the top of the screen. Anyone seen
anything like *this* one, or have any suggestions how it could occur ...
??

Arfa


Its as if the signal was distorted before it ever got to the LCD.
Isn't that possible?

Hi Meat. See reply to Adrian above.

Yeh didn't read it well enough the first time.

Here's a little aside you'll no doubt
find amusing ... Got in this afternoon, and number 2 daughter was doing
some
door painting for us in the house, and had MTV on. At pretty near full
volume, shaking the house ...

Tonight, I'm watching some TV, and the sound is 'wrong'. A bit quiet, and
slightly 'thin' sounding. Then some incidental music came on the
programme,
and it had a very odd 'raspy' sort of a sound to the bass beat. Then I
realised what is wrong. She's only gone and buggered the TV set's built in
sub. Bloody kids.

Mine has his own gear but I did once come home to a house with
rattling windows from the 5.1 system in the tv room. Luckily I like it
loud myself and have 4 Infinity towers, a dual 5.25 center and floor
firing 150 WRMS Kenwood 12" sub thats virtually indestructable
after replacing the stock 12 with a Cerwin Vega 12 sporting a 3" voice
coil

Who needs 'em ?

Hopefully they were at least fun to make.

I guess they probably were ... :-)

The sub in the TV is built into the stand. This is a hulking great Tosh CRT
set, remember. I seem to recall that it is a separate box, before it gets
screwed into the stand, but I can't remember whether it's screwed from the
top, under the TV, or from the sides. I seem to think that it has its own
set of wires going to output sockets on the the back of the TV though, so
maybe I will finish up just disconnecting it, and shoving another sub on
there, hidden behind the TV. I've currently got it shut off in software.
Leaves me with bloody awful sound, but at least no rattly rasp ...

Arfa

"Here's a little aside you'll no doubt
find amusing ... Got in this afternoon, and number 2 daughter was doing
some
door painting for us in the house, and had MTV on. At pretty near full
volume, shaking the house ...

Tonight, I'm watching some TV, and the sound is 'wrong'. A bit quiet,
and
slightly 'thin' sounding. Then some incidental music came on the
programme,
and it had a very odd 'raspy' sort of a sound to the bass beat. Then I
realised what is wrong. She's only gone and buggered the TV set's built
in
sub. Bloody kids.

Mine has his own gear but I did once come home to a house with
rattling windows from the 5.1 system in the tv room. Luckily I like it
loud myself and have 4 Infinity towers, a dual 5.25 center and floor
firing 150 WRMS Kenwood 12" sub thats virtually indestructable
after replacing the stock 12 with a Cerwin Vega 12 sporting a 3" voice
coil

Who needs 'em ?

Hopefully they were at least fun to make.

I guess they probably were ... :-)

The sub in the TV is built into the stand. This is a hulking great Tosh
CRT
set, remember. I seem to recall that it is a separate box, before it gets
screwed into the stand, but I can't remember whether it's screwed from the
top, under the TV, or from the sides. I seem to think that it has its own
set of wires going to output sockets on the the back of the TV though, so
maybe I will finish up just disconnecting it, and shoving another sub on
there, hidden behind the TV. I've currently got it shut off in software.
Leaves me with bloody awful sound, but at least no rattly rasp ...

Arfa


I can't recall ever using the int speakers on my Pana 51". The
speakers on my bedroom set a now defunct Olevia are **** poor and
that's a good review. I hooked a Logitech 5.1 set of pc speakers to it
to cure that problem. One problem I have from the tv audio is when the
display is set to dark or medium room I get a 400hz tone from the
sets audio. It's barely there but annoying. Must be from the circuit
that cuts the voltage down on the CFLs somehow getting into the audio.
**** it I'm not going to worry about it because I watch it
at full power, just have to turn a light on in the room.

The sound is actually quite good on the Tosh. I don't watch a lot of films
or 'big sound' drama, so I've never really bothered with 5.1 amps and the
like. The set has built in Pro Logic surround, with external rear surround
speakers. Good enough for what I want it for.

Anyways, bit of a result today, with any luck. I was on the phone to a mate
at a shop that I do work for, and happened to mention it to him. Apparently,
the sub is located inside the TV's back cover, and the box facing forward in
the stand, is in fact the 'centre' speaker for the surround. Obvious now I
think about it ... So, seems that he has a scrapper at the shop, and he says
that I am welcome to the sub out of it, so I'll pick it up when I'm in there
on Friday :-)

Arfa

Arfa Daily wrote:
I can't for the life of me think what that problem could
be, to cause that symptom. And not any kind of sync issue that I can think
of either. The picture was perfectly stable in both the H and V directions.
Very odd ...

Perhaps it's a "flywheel" PLL sync issue around the part of the circuit
that de-interlaces and reads lines of video into the digital frame buffer.

However it has got problems with recognising the pixel timing of new
lines in the first field, comes in sync after a few lines, successfully
uses the now found timing to digitise the secong field, then, er, forgets?

--
Adrian C